Process for the treatment of oils with aluminum chloride



Feb. 20, 1934.

u. B. BRAY4 El AL PROCESS FOR THE TREATMENT OF OILS WITH ALUMINUM CHLORIDE Filed May 18, 1931 m I 8 v3 k ma hm. flu, Q I mm 7 Wm INVENTORS' CYaaa'e ESmf'z ATTORNEYS Patented Feb. 20, 1934 UNITED STATES PROCESS FOR THE TREATMENT OF OILS WITH ALUMINUM CHLORIDE Ulric B. Bray, Palos Verdes Estates, and Claude E. S wil't, Huntington Park, CaliL, assignors to Union Oil Company of California, Los Angeles, Calif., a corporation of California Application -May 18, 1931. Serial No. 538,236 I 9 Claims. (01. 196-78) 4 This invention relates to a process for the production of lubricating oils.

In the treatment of petroleum lubricating oil distillates, produced from asphalt base crude, 5 with anhydrous aluminum chloride at a temperature range between 150 F. and 400 F., it has been found that the unsaturated oils present in the distillate can be transformed into saturated oils without a material change in the volume of the oil. At these temperatures the anhydrous aluminum chloride causes a saturation of the unsaturated hydrocarbons present without any substantial cracking of the oil, i, e., conversion of the high boiling point hydrocarbons into low boiling point hydrocarbons is not appreciable.

This transformation of the unsaturated hydrocarbons into saturated hydrocarbons results in a product which has a color highly stable to the action of light and a chemical structure less susceptible to oxidation. The treated lubricating oil distillate, however, possesses approximately the same temperature viscosity susceptibility as the original untreated distillate. That is to say, the changes in viscosity with changes in temper- 0 ature, temperature viscosity susceptibility, of both the treated and untreated distillates are substantially the same. Furthermore, the temperature viscosity characteristics of the aluminum chloride treated distillate are approximately the same as all distillates of the same grade produced from asphalt base crude.

It has been shown by one of us that oils contained in asphalt base crudes consist of a mixture of oils, some of which have a low temperature viscosity susceptibility and others which possess a high temperature viscosity susceptibility. Furthermore, it has been shown that this mixture of oils cannot be separated from its asphalt content by ordinary distillation methods without changing certain heavy oils present having a low temperature viscosity susceptibility into oils having a high temperature viscosity susceptibility.

One of us has found that during the heating of an oil containing asphalt, the asphalt induces certain chemical and perhaps physical reactions at relatively low temperature which tends in any prolonged heating to destroy the inherent low viscosity temperature susceptibility of the lubricating fractions. In fact, these temperatures are below thevaporizing temperatures in batch distillation (vacuum or steam) of the lubricating oil fractions which have Saybolt Universal viscosities above 400-500at 100 F., and this even under the highest possible commercial vacuum. It is safe to say that no oil containing asphalt can be topped to the point where fractions above 400-500 seconds at 100 F. are vaporized without a degeneration of those characteristics of the parafiin hydrocarbons which impart to the oil the relatively flat viscosity temperature curve which is characteristic of paraffin hydrocarbons.

To recapitulate the low temperature viscosity susceptibility of certain oilsin a mixed base crude is impaired by distillation even under the most favorable conditions, i. e., the temperature viscosity susceptibilty of certain of the oils present is raised. As a convenient criterion the temperature of the oil during the distillation should not be raised beyond 600-650" F. However, we do not wish to limit ourselves within the foregoing temperature range as the point 7. of impairment by temperature intensity may vary with different crude oils.

The above observations form the subject matter of application Serial No. 466,189.

We have discovered that when these distillates are treated with anhydrous aluminum chloride at a temperature within the range of 150 to 400 F. a saturation of the unsaturated hydrocarbons takes place, unattended by any substantial amount of cracking, but such treatment so does not restore to the oil the temperature viscosity susceptibility possessed by certain of its components in the original crude oil. In other words, once the temperature viscosity susceptibility of the hydrocarbons present has been altered by distillation in the presence of asphalt at elevated temperatures the aluminum chloride treatment will not restore to the oil the low temperature viscosity susceptibility which it possessed in the original undistilled crude.

We have discovered that if the aluminum chloride treatment be carried on with an asphalt base oil which has not been heated to such a temperature to impair its low viscosity temperature susceptibility, it is possible to saturate the unsaturated hydrocarbons present and preserve the low temperature viscosity susceptibility possessed by certain of the residual oils. For example, by treating the above asphalt residual oil 1 with anhydrous aluminum chloride between 150 F. and 400 F. we find that the unsaturated oils present become saturated, the asphalt coagulates into a form easily separable from the oil, the temperature viscosity susceptibility of the final product is approximately the same as that of the untreated oil, and substantially none of the high boiling point oil is converted into low boiling point oil by catalytic action of the metallic halide present.

We have further discovered that by removing the light fractions from the crude oil by distillation under such conditions as not to impair the temperature viscosity susceptibility of certain oils present and then separating the asphalt from the oil by the use of solvents as set forth in the aforesaid application, Serial No. 466,189, that we are able to saturate the solvent extracted oil with a smaller quantity of anhydrous aluminum chloride than is necessary when using the aluminum chloride in the presence of. the asphalt. The addition of the anhydrous aluminum chloride to the residue, consisting of a mixture of oil and asphalt, causes a coalescence or coagulation of the asphalt present into a heavy tar like mass which separates from the oil. In bringing about the coagulation of the asphalt in the petroleum residue an appreciable quantity of the anhydrous aluminum chloride is consumed which is carried down with the precipitated asphalt. Further, the asphalt obtained by the above method resembles soft tar and is therefore of little commercial value as it does not possess physical characteristics comparable to commercial grades of asphalt.

In carrying out the object of our invention, we

prefer to remove all fractions from the crude oil under such conditions as not to impair the temperature viscosity susceptibility of certain oils present, to treat the residual oil produced with a solvent capable of dissolving the oil present, but incapable of dissolving the asphalt as disclosed in the above mentioned application Serial No. 466,189. Solvents capable of bringing about this separation are light petroleum fractions such as naphtha, casinghead gasoline and petroleum fractions normally vaporous at ordinary temperatures and pressures. Further solvents which ,may be used are alcohol, acetone, alcohol and ether or acetone and ether, etc. By the term asphalt is meant constituents of the crude oil precipitated by but undissolved by the foregoing solvents. We prefer to use as our solvent a petroleum fraction obtained by the rectification of natural gasoline. For most purposes a fraction composed of 6.72% ethane, 72.2% propane, 19.91% isobutane and 1.17% normal butane is satisfactory. It will be understood, however, that these merely illustrate the type of fractions which may be used and that the composition may vary. This fraction will hereinafter be referred to as propane for purposes of simplicity.

In carrying out the extraction of the oil with this light liquid fraction, the solution is maintained at a pressure sufiicient to keep the propane in a liquid phase at ordinary temperatures and at pressures of about 120 lbs. per sq. in. The extraction of the oil from petroleum at such pressures results in an asphalt substantially free of oil consisting chiefly of pure bitumen and a solution of oil in the light liquid petroleum fractions. The oil dissolved in the liquid propane contains substantially all the lubricating oil components present in the crude oil and in substantially the same form as they exist in the original crude oil. Some of the oils present in the propane solution possess a low temperature viscosity susceptibility and others possess a high temperature viscosity susceptibility.

The propane solution of oil obtained from asphalt base residuum which is substantially free of asphalt is distilled to remove propane from the extracted oil. The extracted oil is heated in the presence of anhydrous aluminum chloride at a temperature sufficiently high to cause a thorough saturation of the unsaturated hydrocarbons pres- ,residual oils containing asphalt with anhydrous ent but below the point at which any substantial cracking takes place in the presence of the metal lic halide. The aluminum chloride causes a saturation of the unsaturated hydrocarbons to take place, but produces no material effect upon the temperature viscosity susceptibility of the final product. After the saturation of the oil has been completed, the sludge produced by the action is removed by allowing it to settle from the treated oil, after which the oil may be further purified to remove traces of aluminum chloride and other impurities present by acid and alkali treatment.

In order to remove any traces of aluminum chloride from the oil and any other impurities which may be present, the aluminum chloride treated oil substantially free of asphalt may be further treated with acid and alkali.

It is therefore the object of our invention to treat asphalt bearing oil with anhydrous aluminum chloride under such conditions as to cause the asphalt to separate from the oil and to saturate any unsaturated hydrocarbons present in the oil.

It is another object of our invention to treat aluminum chloride under such conditions as to coagulate the asphalt present and saturate the unsaturated hydrocarbons present in the oil without causing any material cracking to take place.

It is a further object of our invention to separate asphalt from oils containing asphalt by such means as not to impair the value of the asphalt or the low temperature viscosity susceptibility of certain components of the crude oil and thereafter to saturate the unsaturated hydrocarbons in the oil by means of anhydrous aluminum chloride at a temperature below which any substantial cracking takes place.

It is a further object of ourinvention to separate oil from asphalt bearing oil by means of a solvent in which the oil is relatively soluble and the asphalt relatively insoluble and thereafter to treat the oil substantially free of asphalt with anhydrous aluminum chloride under such conditions as to saturate the unsaturated hydrocarbons present in the oil without any material conversion of the high boiling point oils into lower boiling point oils.

The figure is one type of apparatus which we may employ to carry out the process of our invention.

Referring more particularly to the figure crude -oil in tank 1 passes through valve 2 to pump 3 which forces it through line 4 into heater 5 where the temperature of the oil is raised suificiently to vaporize all of the light fractions present including gas oil. The heated mass passes from heater 5 through line 6 into fractionation column 7 where by aid of steam introduced in line 90 the light components present are removed through line 8 to condenser 9 where they are liquefied. The noncondensable gas and water are separated from the liquefied hydrocarbons in separator 10. after which the liquefied hydrocarbons pass by means of line 12 to storage tank 13.

The residual oil in fractionation column 7 from which all of the light fractions present have been removed is withdrawn through valve 17 and sent by means of pump 18 through line 19 to cooler 20 where the temperature of the oil is After thorough agitation of the residual oil and propane in agitator 26 it passes by means of line 27 to separator 28 where the undissolved asphalt is separated from the propane solution of oil and is removed through valve 30 and sent by means of pump 31 through line 32 to heater 33 where the temperature of the mass is raised sufficiently to vaporize all of the propane and water present. The heated mass passes from heater 33 to line 34 to separator 35 where the asphalt free from moisture and propane is withdrawn through valve 36 and sent by means of line 37 to tank 38. The mixture of propane and water vapor passes from settling chamber 35 through line 39 to condenser 40 where the water vapor present is condensed. The mixture of propane vapor and water passes into separator 41 where the water is separated from the propane and is removed through valve 42 and line 43.- The propane vapor passes from separator 41 by means of line 44 to compressor 45 where it is compressed and sent by means of line 44' to condenser 9'? where it is condensed and passes by means of line 46 to propane storage tank 22.

The propane solution of oil free from asphalt in separator 28 passes by means of line 29 to pump 47 which forces it through line 29 into evaporator 48 where the propane is removed by the aid of steam introduced through closed steam coil 52 and passes by means of valve 49 to line 50, thence to compressor 51 where it is compressed and is sent by means of line to condenser 97 where it is condensed and passes by means of line 46 to propane storage tank 22.

If it is desirable to remove any remaining moisture in the oil at this point in the process, this may be accomplished by regulating the heat introduced by steam in closed coil 52 of evaporator 48. The moisture present in the oil is vaporized along with the propane and finds its way into tank 22 where it separates by a difference in specific gravity and is removed from the storage tank by means of valve 89.

The oil in evaporator 48 is withdrawn through valve 53 and sent by means of pump 54 through line 91 into agitator 55. Anhydrous aluminum chloride is introduced into agitator 55 through man hole 56. In order to insure thorough contact between the oil and the anhydrous aluminum chloride the agitator 55 is provided with a series of paddles 59 mounted upon shaft 92 which is rotated by means of pulley 58. In order to keep the oil at the temperature necessary to carry out the reaction, hot water or steam is introduced through line 5'7. This temperature varies from approximately 150 F. to 400 F., depending upon the oil and the rate of the reaction. We prefer to use a temperature of about 200 F.

. During the contact period between the oil and the anhydrous aluminum chloride, any low boiling point hydrocarbons formed are removed through line 60 to condenser 61 where they are condensed and pass by means of line 62 to any suitable storage for further treatment which may be required. The tars, polymerization products and other reaction products in agitator 55 are removed through pipe 63 and valve 64.

The treated oil free from tar and polymerization products in agitator 55 is removed through valve 65 and sent by means of pump 66 through line 93 to cooler 6'7 where the temperature of the oil is lowered to approximately 100 F., after which it passes into line 68 where it meets a stream of sulphuric acid coming from tank 69 through valve 70, ptunp '71 and line 94. The mixture of oil and acid passes through line 68 to agitator 72 where it is thoroughly mixed, after which it passes by means of line 73 to settling chamber 74 where the sludge formed is allowed to settle out and is removed through valve 75 and line 76. The acid treated oil in settling chamber 74 is removed through line '77 into washingtower 78 where it is washed with caustic soda introduced from tank 79 through valve 80, pump 81 and line'82. The spent alkali is removed from washing tower '78 through valve 95 and line 96. Any excess alkali' in the oil is removed by washing the oil contained in washing tower 78 with water introduced from tank 83 through valve 84, pump 85 and line 82. The washing water carrying alkali and other dissolved material from the oil is removed from washing tower 78 through valve and line 96. The treated oil in washing tower '78 is removed through valve 86 and passes by means of line 8'? to tank 88. If desired the oil may be distilled to remove any remaining light fractions present.

The foregoing description of the process is merely descriptive of one form of apparatus in which we may carry out our process and is not to be understood as limiting the scope of our invention.

We claim 1. A process for the treatment of oil containing asphalt to produce lubricating oil which comprises commingling said oil with an asphalt precipitating solvent to separate asphalt, removing the asphalt from the oil dissolved in said solvent, removing the solvent from the substantially asphalt free oil, treating the substantially asphalt free oil with aluminum chloride at a temperature below which any substantial cracking takes place to react with the undesired constituents present in the oil and separating the aluminum chloride and reaction products from the treated oil.

2. A process for the treatment of oil containing asphalt to produce lubricating oil which 1 5 comprises commingling said oil with a liquefied normally gaseous hydrocarbon solvent to separate asphalt, removing the asphalt from the oil dissolved in said solvent, removing the solvent from the substantially asphalt free oil, treating the substantially asphalt free oil with aluminum chloride at a temperature below which any substantial cracking takes place to react with the undesirable constituents present in the oil and removing the aluminum chloride and reaction products from the treated oil.

3. A process for the treatment of oil containing asphalt to produce lubricating oil which comprises commingling said oil with liquid propane to separate asphalt, removing the asphalt from the oil dissolved in liquid propane, removing the propane from the substantially asphalt free oil, treating the substantially asphalt free oil with aluminum chloride at a temperature below which any substantial cracking takes place to react with the undesirable constituents present in the oil, and removing the aluminum chloride and reaction products from the treated oil.

4. A process for the treatment of oil containing asphalt to produce lubricating oil which comprises distilling said oil to a temperature not exceeding 650 F. and removing the fractions vaporized by said distillation, commingling the residual oil remaining after the distillation with an asphalt precipitating solvent to precipitate the Z45 asphalt and dissolve the oil, separating the precipitated asphalt from the oil dissolved in said solvent, removing the solvent from the substantially asphalt free oil, contacting the substantially asphalt free oil with aluminum chloride at 150 6. A process as in claim 4 in which the solvent is a. liquefied normally gaseous hydrocarbon.

7. A process as in claim 4 in which the solvent is liquid propane.

8. A process as in claim 1 in which the treated oil is treated with acid and alkali.

9. A process as in claim 3 in which the treated oil is treated with acid.

ULRIC B. BRAY. .CLAUDE E. SWIFT. 

